Trailing arm suspension beam assembly

ABSTRACT

A suspension assembly includes an axle member, a first trailing beam assembly and a second trailing beam assembly. The first trailing beam assembly and the second trailing beam assembly each include a first end operably coupled to a vehicle frame and a second end that includes a downwardly opening recess, wherein the recess includes an outer periphery, the axle member is positioned within the recess, and wherein a weld extends about the entire periphery of the recess, thereby securing the trailing beams to the axle member.

BACKGROUND OF THE INVENTION

The present invention relates to an axle suspension system for heavyvehicles, and in particular to a trailing arm assembly with increasedstrength and which is adapted to increase the durability of anassociated vehicle axle.

A variety of vehicle suspension systems utilizing air springs have beendeveloped for use within semi-tractor trailer and other heavy dutyvehicles. These systems control the relative position of the chassiswith respect to an associated axle or axles and also to cushion therelative movement of the axle(s) toward the chassis frame. Thesuspension systems, and particularly the components such as the trailingarms and axle assemblies thereof, undergo significant stress duringoperation of the vehicle. Specifically, the connection between thetrailing arms and the associated axle undergo significant stress whentypical operational loads are exerted thereon, both in the vertical andlateral directions. While many systems have been developed to reducesuch stress, previous approaches have been relatively expensive, and attimes only marginally effective.

There is a need for a lightweight and inexpensive air spring suspensionsystem that reduces the stress exerted between the trailing arms of thesuspension system and the associated axle.

BRIEF DESCRIPTION OF THE DRAWINGS

In the drawings:

FIG. 1 is a perspective view of a suspension system that includes atrailing arm assembly embodying the present invention;

FIG. 2 is a side elevational view of the suspension system, wherein abraking assembly has been removed to better illustrate the trailing armassembly;

FIG. 3 is a perspective view of a first embodiment of the trailing armassembly;

FIG. 4 is a side elevational view of the first embodiment of thetrailing arm assembly;

FIG. 5 is a top plan view of the first embodiment of the trailing armassembly;

FIG. 6 is a perspective view of end of the first embodiment of thetrailing arm assembly;

FIG. 7A is an enlarged, partial perspective view of the suspensionsystem, and in particular the trailing arm assembly;

FIG. 7B is an enlarged, partial perspective view of the suspensionsystem, and in particular the trailing arm assembly;

FIG. 8 is an enlarged side elevational view of the first embodiment ofthe trailing arm assembly;

FIG. 9 is a perspective view of a second embodiment of the trailing armbeam assembly;

FIG. 10 is a perspective view of a trailing arm beam of the secondembodiment of the trailing arm beam assembly;

FIG. 11 a is a rear perspective view of a spring support member of thesecond embodiment of the trailing arm beam assembly;

FIG. 11 b is a front perspective view of the spring support member ofthe second embodiment of the trailing arm beam assembly;

FIG. 12 is a perspective view of a third embodiment of the trailing armassembly;

FIG. 13 is a side elevational view of the third embodiment of thetrailing arm assembly;

FIG. 14 is a top plan view of the third embodiment of the trailing armassembly;

FIG. 15 is a perspective view of a fourth embodiment of the trailingarm;

FIG. 16 is a side elevational view of the fourth embodiment of thetrailing arm;

FIG. 17 is a partial cross-sectional top view of the fourth embodimentof the trailing arm taken along the line XVII-XVII, FIG. 16; and,

FIG. 18 is a top plan view of a plurality of a fourth embodiment of thetrailing arm positioned within a rectangular casting core box.

DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS

For purposes of description herein, the terms “upper,” “lower,” “right,”“left,” “rear,” “front,” “vertical,” “horizontal,” and derivativesthereof shall relate to the invention as oriented in FIGS. 1 and 2.However, it is to be understood that the invention may assume variousalternative orientations and step sequences, except where expresslyspecified to the contrary. It is also to be understood that the specificdevices and processes illustrated in the attached drawings, anddescribed in the following specification are exemplary embodiments ofthe inventive concepts defined in the appended claims. Hence, specificdimensions and other physical characteristics relating to theembodiments disclosed herein are not to be considered as limiting,unless the claims expressly state otherwise.

The reference numeral 10 (FIGS. 1 and 2) generally designates a heavyduty vehicle suspension system that includes a plurality of trailing armassemblies 12 each embodying the present invention. In the illustratedexample, the vehicle suspension system 10 includes a pair of tandem axleassemblies including a forward axle assembly 14 and a rearward axleassembly 16, respectively. Each of the axle assemblies 14, 16 issupported by an associated trailing arm assembly 12. Each trailing armassembly 12 includes a trailing arm or beam 18 having a first end 20 anda second end 21. The first end 20 is pivotally supported by anassociated hanger bracket 22 that is fixedly attached to and extendsdownwardly from a longitudinally extending vehicle frame member 24.Specifically, the first end 20 of the hanger bracket 22 is pivotallycoupled to the associated hanger bracket 22 via a bushing assembly 25 topivot about a pivot axis 26. An air spring assembly 28 is positionedbetween an air spring support 30 of the trailing arm assembly 12 and thevehicle frame member 24.

As best illustrated in FIGS. 3-6, each trailing arm assembly 12 includesthe trailing arm 18 and the air spring support 30. The trailing arm 18includes a body portion 32 having a bushing aperture 34 located at thefirst end 20, and an axle adapter 36 located at the second end 21. Thebody portion 32 comprises a metal alloy, is preferably integrally castas a single piece, and includes an I-shaped cross-sectionalconfiguration including a vertical web portion 40, a bottom flange 42,and an upper flange 44.

The axle adapter 36 of the trailing arm 18 includes an outwardly, andspecifically downwardly-opening, arcuately-shaped recess 46 thatreceives a vehicle axle 48 (FIGS. 7A, 7B) of the axle assembly 14, 16therein. The axle adapter 36 further includes a pair of laterallyextending forward weld ears 50 and a pair of laterally extendingrearward weld ears 52. The recess 46 and the weld ears 50, 52 cooperateto define an axle seat periphery 54, about which the trailing arm 18 iswelded to the associated axle 14, 16. In assembly, a single continuousweld 55 is preferably applied about the entire length of the axle seatperiphery, thereby reducing the number of weld ends and increasing thedurability of the axle connection. Specifically, welding about theentire axle seat periphery between the axle adapter 36 and the axle 48,reduces stress risers associated with using multiple welds, and allows arelatively thin axle wall to be utilized. As best illustrated in FIG. 8,the forward weld ears 50 and rearward weld ears 52 are positioned andconfigured with regards to the associated axle 14 such that the weld 55positioned proximate a leading edge 65 of the forward weld ears 50preferably forms a negative angle α with the horizontal of between about30° to about 45°, and more preferably of about 35°, and such that theweld 55 positioned proximate a trailing edge 67 of the rearward weldears 52 preferably forms a positive angle β the horizontal of betweenabout 25° and about 45°, and more preferably of about 8°, therebyreducing the stress exerted on the axle connection by typicaloperational loads. The location of the weld ears 50, 52, and thus theassociated welds, significantly reduces the stress swing exerted on theweld ears 50, 52 and the welds 55.

The air spring support 30 (FIGS. 3-6) of the trailing arm assembly 12includes a top plate or spring support plate 56 upon which theassociated air spring assembly 28 is supported, and a pair of supportbrackets 58 extending between the second end 21 of the trailing arm 18and the top plate 56. Specifically, each support bracket 58 is generallytriangularly shaped and includes a forward edge 60 weldably secured to arearward face 61 of the second end 21 of the trailing beam 18, a topedge 62 weldably secured to an underside of the top plate 56, and adownwardly facing edge 64. The top plate 56 is positioned with respectto the support brackets 58 such that a forward edge portion 66 of thetop plate 56 overlies the upper flange 44 of the trailing arm 18. Theforward edge portion 66 includes a welding window 68 which receives aweld, thereby securing the top plate 56 to the trailing arm assembly 12.It is noted that the weld window 68 is located on an outboard side ofthe top plate 56 such that the top plate 56 is welded to a draft surfaceof the trailing arm 18, thereby causing the top plate 56 to “tilt” tothe outboard side of the trailing arm 18. Specifically, the springsupporting surface 57 of the top plate 56 is outwardly canted withregards to at least one of the central axis member 39 and the centralaxis of the pivot axis 26 at an angle ∞ of preferably within the rangeof between about 0.5° and about 3°; and more preferably within the rangeof between about 0.5° and 1.5°. As a result, loading of the overallsuspension system 10 causes the overall trailing arm assembly 12 to“tilt” inboard such that the top plate or air spring mounting plate 56is substantially parallel to upper air spring mounting plates 70(FIG. 1) attached to the frame member 24. The resulting parallelrelationship between the top plate 56 and the associated upper airspring mounting plate 70 reduces the wear exerted on the air springassembly 28 during operation.

The reference numeral 12 a (FIGS. 9-11 b) generally designates anotherembodiment of the trailing arm assembly of the present invention. Sincethe trailing arm assembly 12 a is similar to the previously describedembodiment of the trailing arm assembly 12, similar parts appearing inFIGS. 1-8 and FIGS. 9-11 b respectively are represented by the same,corresponding reference numeral, except for the suffix “a” in thenumerals of the latter. In the illustrated example, the trailing armassembly 12 a includes the trailing arm 18 a and the air spring support30 a. The second end 21 a of the trailing arm includes a pair ofrearwardly extending eyelets or hinge members 100 having bolt-receivingapertures 102 extending therethrough. The air spring support 20 a isgenerally arcuately-shaped and includes a forwardly-extending couplingportion 104 and a rearwardly-located spring support plate 56 a. Thecoupling portion 104 includes a pair of laterally-spaced plate portions106 that flank the hinge members 100 and include apertures 108 thatcorrespond to the apertures 102 and that receive bolts 110, therebycoupling the air spring support 20 a with the trailing arm member 18 a.The end surface 111 of the trailing arm 18 a is machined and abuts amachined surface 113 of the air spring support 30 a, so as to supportdownward forces exerted by the air spring 28 onto the air spring support30 a.

The reference numeral 12 b (FIGS. 12-14) generally designates anotherembodiment of the trailing arm assembly of the present invention. Sincethe trailing arm assembly 12 b is similar to the previously describedembodiment of the trailing arm assembly 12, similar parts appearing inFIGS. 1-8 and FIGS. 12-14 respectively are represented by the same,corresponding reference numeral, except for the suffix “b” in thenumerals of the latter. In the illustrated example, the trailing armassembly 12 b includes the trailing arm 18 b and the air spring support30 b. The second end 21 b of the trailing arm 18 b is rearwardly,downwardly sloped and is defined by a rearward surface 80 and a ledge 82that is vertically offset below an uppermost surface of the trailing arm18 b. The forward edge 60 b of each of the support brackets 58 b of theair spring support 30 b has a forwardly-opening concave shape that ispositioned about a complimentary convex shape of the rearward surface 80of the trailing arm 18 b. The forward edge portion 66 b of the top plate56 b cantilevers and extends over the ledge 82 of the second end 21 b ofthe trailing arm 18 b and is secured thereto via a weld located withinthe welding window 68 b. The air spring support 30 b is further securedto the associated trailing arm 18 b via welds 84, while the top plate 56b and the support brackets 58 b are secured to one another via aplurality of welds 86. This particular configuration allows the overallheight of the trailing arm assembly 12 b to be minimized, and allowsvertical loads from the air spring assemblies 28 to be supported by thetrailing arm 18 b through compressive stresses within the ledge 82 andrearward surface 80 of the trailing arm 18 b.

The reference numeral 18 c (FIGS. 15-17) generally designates anotherembodiment of the trailing arm of the present invention. Since thetrailing arm 18 c is similar to the previously described embodiment ofthe trailing arm 18, similar parts appearing in FIGS. 3-6 and FIGS.15-17 respectively are represented by the same, corresponding referencenumeral, except for the suffix “c” in the numerals of the latter. Asbest illustrated in FIGS. 16 and 17, the overall height h definedbetween an uppermost portion of the recess 46 c and the substantiallyperpendicularly located upper surface of the trailing arm 18 c isreduced. This reduction in overall height is accomplished by providing arelatively thick portion 40 c′ to the web portion 40 c of the trailingarm 18 c proximate the recess 46 c, whereat the portion 40 c of the webportion 40 c has a relatively greater thickness t″ compared to thethickness t′ of the web portion 40 c extending along the remaininglength of the trailing beam 18 c. Preferably, the thickness t″ isbetween 2 and 8 times greater than the thickness t′. It is noted thatthe trailing arm 18 c does not include vertically extendingreinforcement webs proximate to the forward edge of the recess 46 c,thereby providing a reduction in the overall weight of the trailing arm18 c.

The reference numeral 18 d (FIG. 18) generally designates yet anotherembodiment of the trailing arm of the present invention. Since thetrailing arm 18 d is similar to the previously described embodiment ofthe trailing arm 18, similar parts appearing in FIGS. 3-6 and FIG. 18respectively are represented by the same, corresponding referencenumeral, except for the suffix “d” in the numerals of the latter. Thetrailing arm 18 d is provided with an overall curvalinear body shapethereby allowing “nesting” of a plurality of trailing arms 18 d with oneanother within an associated casting core box 88. The nesting of thetrailing arms 18 d with one another reduces the overall area requiredwithin the casting core box 88, thereby increasing yield per mold duringthe casting process, resulting in a reduction in costs for manufacturingeach beam and increasing the overall efficiency of the foundry.

The present inventive trailing arm assembly and related suspensionsystem increases the durability of the associated axle connection, whilesimultaneously reducing the weight. The trailing arm assembly andsuspension system is efficient in assembly and use, is capable of a longoperating life, and is particularly well adapted for the proposed use.

The above description is considered that of the preferred embodimentsonly. Modifications of the invention will occur to those skilled in theart and to those who make or use the invention. Therefore, it isunderstood that the embodiments shown in the drawings and describedabove are merely for illustrative purposes and not intended to limit thescope of the invention, which is defined by the following claims asinterpreted according to the principles of patent law, including thedoctrine of equivalents.

The invention claimed is as follows:
 1. A suspension assembly,comprising: an axle member having a central axis; a first trailing beamassembly including a first trailing beam and a first spring support, thefirst trailing beam having a first end pivotably coupled to a vehicleframe about a first pivot axis and having a second end operably coupledto the axle member, the first spring support including a spring supportplate having a spring supporting surface that is outwardly canted withrespect to at least a select one of the central axis of the axle memberand the first pivot axis prior to coupling the first trailing beam withthe vehicle frame; and a second trailing beam assembly including asecond trailing beam and a second spring support, the second trailingbeam having a first end pivotably coupled to a vehicle frame about asecond pivot axis and having a second end operably coupled to the axlemember, the second spring support including a spring support platehaving a spring supporting surface that is outwardly canted with respectto at least a select one of the central axis of the axle member and thesecond pivot axis prior to coupling the second trailing beam with thevehicle frame.
 2. The suspension assembly of claim 1, wherein the springsupporting surface of the first spring support is outwardly canted withrespect to at least a select one of the central axis of the axle memberand the first pivot axis within a range of from about 0.5° to about 3°,and wherein the spring supporting surface of the second spring supportis outwardly canted with respect to at least a select one of the centralaxis of the axle member and the second pivot axis within a range of fromabout 0.5° to about 3°.
 3. The suspension assembly of claim 2, whereinthe spring supporting surface of the first spring support is outwardlycanted with respect to at least a select one of the central axis of theaxle member and the first pivot axis within the range of from about 0.5°to about 1.5°, and wherein the spring supporting surface of the secondspring support is outwardly canted with respect to at least a select oneof the central axis of the axle member and the second pivot axis withinthe range of from about 0.5° to about 1.5°.
 4. A suspension assembly,comprising: an axle member having a central axis; a first trailing beamassembly, comprising: a first trailing beam having a first end pivotablycoupled to a vehicle frame about a first pivot axis, a second endoperably coupled to the axle member, and an uppermost surface; and afirst spring support including a spring support plate having a springsupporting surface that is located vertically lower than the uppermostsurface of the first trailing beam subsequent to the first trailing beambeing coupled to the vehicle frame; and a second trailing beam assembly,comprising: a second trailing beam having a first end pivotably coupledto the vehicle frame about a second pivot axis, a second end operablycoupled to the axle member, and an uppermost surface; and a secondspring support including a spring support plate having a springsupporting surface that is located vertically lower than the uppermostsurface of the second trailing beam subsequent to the second trailingbeam being coupled to the vehicle frame.
 5. The suspension assembly ofclaim 4, wherein the first trailing beam includes rearwardly extendingcoupling portion including an upper surface that is located below theuppermost surface of the first trailing beam, and wherein the springsupport plate of the first spring support is fixedly secured to therearwardly extending coupling portion to the first trailing beam.
 6. Thesuspension assembly of claim 5, wherein the spring support plate of thefirst spring support includes an aperture extending therethrough thatoverlaps with the rearwardly extending coupling portion of the firsttrailing beam, and wherein the spring support plate of the first springsupport is secured to the first trailing beam by a weld that extends atleast partially about the aperture.
 7. The suspension assembly of claim4, wherein the first trailing beam includes a convex-shaped rearwardlyextending surface, and wherein the first spring support includes aconcave-shaped forwardly extending surface that receives theconvex-shaped rearwardly extending surface of the first trailing beamwhen the first trailing beam is secured to the first spring support.